The present invention provides for a high-voltage, low-volume ceramic capacitor module. More particularly, this invention relates to a high-voltage ceramic capacitor fabricated using surface-mount chip capacitor technology, and capable of being integrated into various electrical systems in a manner which would minimize the amount stray inductance (also denoted as "L.sub.Stray ") introduced into the system.
Electrical power conversion (from AC to DC, DC to AC, or DC to DC) is increasingly being accomplished by solid-state devices (IGBTs, MCTs, FETs, BITs, etc.) in conjunction with capacitors, inductors and resistors. Many examples of power circuit topology that can be used to accomplish this power conversion may be found in the prior art. A typical example of such circuitry for converting direct current electrical power to alternating current electrical power is shown in FIG. 1A. In FIG. 1A, an inverter, comprised of power switching devices 1, 2, 3 and 4, is gated so that an alternating voltage is produced across the circuit's output. A typical gating sequence to produce such a voltage would be to sequentially switch between a state where devices 1 and 4 were "on" (conductive) while devices 2 and 3 were "off" (non-conductive), and a state where devices 1 and 4 were "off", and devices 2 and 3 were "on". Similar topologies are used in DC-to-DC converters, DC-to-multiphase AC converters, and AC to DC converters.
One of the primary problems encountered in designing and producing such power converters is the minimization of so-called stray inductances. These are the inductances introduced by capacitors employed within the converters, the cabling typically used to connect these capacitors to the positive and negative power supply terminals, and by the power switching devices which are employed within these converters. The inductances introduced by these sources all contribute to the magnitude of the total stray inductance for the converter, and can be modeled as a lumped stray inductance (see FIG. 1B).
A certain amount of such stray inductance will be present in all power converters, simply as a result of unavoidable physical constraints upon the capacitor size, lead lengths, and interconnect wiring between the power switching devices and the capacitors. This stray inductance, while typically only several microhenrys in magnitude, is nonetheless significant in its impact upon converter performance.
Typically, in such voltage converters, the output switching devices are opened and closed at high frequencies, and each time the switching devices are opened the energy stored in the stray inductance (which is equal to 1/2I.sup.2 L.sub.Stray joules) must be dissipated. At multiple kilohertz switching frequencies, the amount of power to be dissipated becomes appreciable. Furthermore, at such high frequency switching rates, the act of dissipating this energy causes high-voltage stresses to be imposed upon the switching devices, and thereby reduces the power handling capability of the overall converter.